‘I agree,’ he said simply. ‘Anything other than Bolton helping our friend through the window is entirely too coincidental. Our problem here won’t be proving it wasn’t an accident, though, it’s still placing Bolton inside the building. There’s a good chance that …’

He stiffened, and his voice tailed off as he stared through the window.

‘What? What you thinking?’ Porter prompted.

‘I’m thinking I hope that’s what I think it is,’ he said, leaning and pointing off to the right.

Porter slid off the desk and waited for Styles to step aside, then peered out to see what all the fuss was about.

The road was quiet, although the hum of machinery could be heard from a nearby factory. ‘Where am I looking?’

‘Right up there.’ Styles pointed again, his arm indicating a line of sight above street level, and Porter followed his direction. He narrowed his eyes, still unsure what he was meant to be looking at, until he focused his attention a little higher to allow for the slight difference in their vantage points. Lamp posts were evenly spaced long the road, with one every hundred feet or so. Most of the other buildings on the street were one or two storeys, and the lights atop the curved neck of the poles looked down upon the rooftops. The one closest to them on the opposite side of the street, however, was slightly different from its neighbours. A small dark shape clung to the top of the pole just below the light.

‘What is it?’

‘I’m guessing it’s some sort of CCTV,’ said Styles, without taking his eyes off it. ‘We can check with whoever worked the scene to make sure they’ve got their hands on the footage. Whether it shows anything worthwhile is another matter, but with a bit of luck I think we may have just found a way to place Mr Bolton where we need him to be.’

They swung by Darent Valley Hospital for their last stop, and saw a man sitting by her bedside as they entered the room. He held her right hand encased between his, his head bowed, his lips trembling ever so slightly. Their footsteps gave them away and the man’s head snapped up, aware that he was no longer alone.

‘Hi there,’ said Porter, apologetic at disturbing the private moment. ‘We work with Evie. Are you a relative or a friend?’

The man nodded and stood, smoothing out the creases in his pale blue sweater as he did. Porter guessed he was in his late fifties, his hair so grey it could pass for white. His face showed the strain of his bedside vigil, and Porter wondered how many of the creases in his forehead and around his eyes had been carved deeper by the worry of the last few days.